Generally, a swash plate type compressor which mainly has been used for air conditioning systems of vehicles includes a disc shape of swash plate rotatably installed at a drive shaft receiving rotating power from an engine to change a tilt angle thereof, and a plurality of pistons arranged along a circumference of the swash plate via shoes while reciprocally moving in cylinder bores formed in a cylinder block to suck refrigerant gas, compress sucked refrigerant gas, and then discharge compressed refrigerant gas.
Recently, a variable displacement swash plate type compressor capable of accomplishing precise temperature control by controlling strokes of pistons due to changing a tilt angle of the swash plate depending on a change of thermal load has been proposed. At the same time, the tilt angle is continuously varied to reduce abrupt torque fluctuation of an engine caused by the compressor, thereby improving ride comfort of a vehicle.
In the Korean Patent Registration No.529716 (Patentee: Doowon Technical College, Doowon Electronic CO., Ltd), an exemplary embodiment of such a variable displacement swash plate type compressor is disclosed.
As shown in FIGS. 1 and 2, the variable displacement swash plate type compressor of the prior art includes a cylinder block 11 having a plurality of cylinder bores 11a formed in a longitudinal direction of the compressor and comprising a body portion of the compressor, a front housing 12 disposed at a front end of the cylinder block 11 to form a swash plate chamber 12a, a drive shaft 14 rotatably supported by the cylinder block 11 and the front housing 12, a lug plate 18 fixedly installed at the drive shaft 14 in a swash plate chamber 12a of the front housing 12, a rear housing 13 having a suction chamber 13a and a discharge chamber 13b and disposed at a rear end of the cylinder block 11, a swash plate 15 having a disc shape and being rotated by the lug plate 18 to vary a tilt angle thereof, a spring 17 supported between the lug plate 18 and the swash plate 15, and pistons 20 coupled to the swash plate 15 via shoes 21 to be slidably reciprocally accommodated in the cylinder bores 11a. 
A suction port 16a and a discharge port 16b are respectively formed in a valve plate 16 installed between the rear housing 13 and the cylinder block 11, to respectively connect the cylinder bore 11a to the suction chamber 13a and the cylinder bore 11a to the discharge chamber 13b. 
A suction valve (not shown) and a discharge valve (not shown) are respectively provided in a suction port 16a and a discharge port 16b to open and close the suction port 16a and the discharge port 16b, by a pressure change due to reciprocal movement of the pistons 20.
As shown in FIG. 3A, the spring 17 is supported between a sleeve 19 and the lug plate 18, the swash plate 15 being rotatably installed to the sleeve 19 which is located at the inside of the swash plate 15. The spring 17 pushes the swash plate 15 backward at normal times when external force is not applied so as to maintain a minimum tilt angle of the swash plate 15.
Accordingly, as shown in FIG. 3B, when the swash plate 15 is tilted, the sleeve 19 overcomes elastic force of the spring 17 and moves forward. And a lower stopper 15a of the swash plate 15 is contacted with the rear end of the lug plate 18.